What does the pink arrow extending above the Horizontal Situation Indicator (HSI) indicate during an IFR flight?

The pink arrow extending above the Horizontal Situation Indicator (HSI) during an IFR flight indicates the rate of turn. This feature is part of the HSI's functionality, providing pilots with critical visual guidance on the turn rate of the aircraft. When a pilot is turning, especially in an instrument flight scenario, it is crucial to monitor the rate of turn to ensure that the turn is executed at the correct rate, maintaining aircraft control and awareness of performance during various phases of flight.

Understanding the rate of turn is essential for maintaining safe flight operations, particularly while flying in low visibility or when following air traffic control instructions. This capability helps pilots manage their aircraft's orientation relative to the intended flight path, allowing for smooth and precise navigation.